There were bands toying with melodic rock as we know it prior to the mid 70's...which is just a continuation of pop and other radio rock but with more edge. But they mainly had a song here and/or there,not albums full of it. I'd agree that Boston really visualized the idea that an entire album could be radio-friendly rock. At least..with hindsight by tons of bands. I doubt even Scholz thought that he was inventing 'radio rock' while writing the material. It just happened to tweakl all those boxes for what tons of people wanted from a band--and the rest is history. T